Biodiesel is mainly the methyl ester of fatty acids that is formed through the transesterification of long-chained fatty acids with an alcohol (methanol). The fatty acid esters of natural fats consist mainly of triglycerides, whereby a water-soluble glycerol that is unacceptable as biodiesel is released in the transesterification. Further, an alcohol (methanol) mixed into the aqueous glycerol solution and salts of fatty acids (later soap) are released in the process. This fraction containing glycerol, alcohol and soap still has, particularly with regard to the soap, a high energy content. Theoretically, 10% by weight of glycerol is generated from the triglyceride. Depending on the process conditions, the proportion of the soap can vary greatly and rise up to tens of percent from the original total amount of triglyceride. Since the soap compounds are dispersed and partly dissolved in the aqueous solution of the formed glycerol, their separation from the aqueous solution is difficult. The soap disrupts the phase between the fat-soluble fatty acid esters and the water-soluble glycerol and tends to form different degrees of emulsions, creating a challenging problem in large-scale processes with regard to separation techniques. Removal of the alcohol, such as methanol, would also require expensive vacuum distillation. Thus, it can be concluded, that manufacturing biodiesel using the afore-described method in modern technology is underutilization of the most energy-rich parts of the raw material. Purification of the compounds generated in the process in order to increase their value of use is highly uneconomical already merely with regard to the purification steps required.
To a great extent due to the aforementioned reasons, no cost-effective solutions for the utilization of the mixture of aqueous glycerol, soap and alcohol (methanol) have been found.
There are no business economically advantageous solutions for transforming the multi-component mixtures containing glycerol as a component into commercial products. The significance of this technological deficiency is emphasized particularly as the interest grows towards renewable sources of energy raw materials in addition to the fossil raw materials.